1. Technical Field
The embodiments description herein relate to a semiconductor device, and more particularly to a data output driving circuit and a method for controlling a slew rate thereof.
2. Related Art
As shown in FIG. 1, a conventional data output driving circuit includes an on-die termination correction circuit 1 and a plurality of drivers (DRVs) 2. The on-die termination correction circuit 1 generates first codes “Pcode <0:K−1>” and second codes “Ncode <0:K−1>” to determine driving resistances of the plurality of drivers 2. The drivers 2 drive data signals “updo” and “dndo” according to the first and second codes “Pcode <0:K−1>” and “Ncode<0:K−1>” to output the data signals “updo” and “dndo” through a data input/output pad DQ. The drivers 2 are connected to the data input/output pad DQ in parallel.
Since the drivers 2 have the same structure, the driver 2, which receives the first and second codes “Pcode<0>” and “Ncode<0>”, among the plurality of drivers 2 is representatively described with reference to FIG. 2. The driver 2 includes a plurality of NAND gates NR1 and NR2, a plurality of inverters IV1 and IV2, a plurality of resistors RP1, RP2, RN1, and RN2, a pull-up main driver M0, pull-up pre-drivers M2 and M3, a pull-down main driver M1, and pull-down pre-drivers M4 and M5.
If the first code “Pcode<0>” is activated in the driver 2, then the pull-up pre-drivers M2 and M3 drive the data signal “updo” to generate a pull-up driver driving signal “up”. The pull-up main driver M0 drives the data input/output pad DQ with a data level by using a supply voltage according to the pull-up driver driving signal “up”. If the second code “Ncode<0>” is activated in the driver 2, then the pull-down pre-drivers M4 and M5 drive the data signal “dndo” to generate a pull-down driver driving signal “dn”. The pull-down main driver M1 drives the data input/output pad DQ with a data level by using a ground voltage according to the pull-down driver driving signal “dn”.
A slew rate of data output through the data input/output pad DQ is determined according to the pull-up driver driving signal “up” and the pull-down driver driving signal “dn”. The pull-up driver driving signal “up” and the pull-down driver driving signal “dn” are affected by variations in the operational conditions, that is, variations of a process/voltage/temperature (PVT). However, a conventional data output driving circuit has no hardware and software capable of controlling the pull-up and pull-down driver driving signals “up” and “dn” according to variations in the operational conditions. Accordingly, in a conventional data output driving circuit, the slew rate of the final output data is undesirably changed due to the variations in the operational conditions, such that a loss of a data may occur or an operational frequency may be limited.